 Otto Hahn is considered a pioneer of radioactivity and radiochemistry with the discovery of nuclear fission in 1938, the scientific and technological basis of atomic energy.The bio-chemist Adolf Butenandt independently worked out the molecular structure of the primary male sex hormone of testosterone and was the first to successfully synthesize it from cholesterol in 1935.Germany has been the home of many famous inventors and engineers, such as Johannes Gutenberg, who is credited with the invention of movable type printing in Europe; Hans Geiger, the creator of the Geiger counter; and Konrad Zuse, who built the first electronic computer.